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为什么添加3个字节失败,但DWORDs成功[duplicate]

addition masm x86 assembly

0

Jishan · 技术社区 · 8 年前

嘿,所以当我运行以下代码时,会出现此错误:

1>------ Build started: Project: Project, Configuration: Debug Win32 ------
1>  Assembling [Inputs]...

1>assign2.asm(32): error A2022: instruction operands must be the same size

1>assign2.asm(33): error A2022: instruction operands must be the same size

1>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\BuildCustomizations\masm.targets(49,5):

 error MSB3721: The command "ml.exe /c /nologo /Zi /Fo"Debug\assign2.obj" /Fl"Project.lst" 

/I "c:\Irvine" /W3 /errorReport:prompt  /Taassign2.asm" exited with code 1.

========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

下面是代码,当我试图从usPop中减去ml1337skillz并将结果存储到Difference中时会发生这种情况。(请记住,我刚刚开始学习这个领域:)

TITLE Learning      (learning.asm)

INCLUDE Irvine32.inc

secondE = 00000000010001010000000000000000b

.data

myName BYTE "John Smith"

nameLen = ($ - myName)

nationalDebt QWORD 7975482431119.47d

usPop DWORD 313900000d

kindaNegative SDWORD -2147483648d

my1337Sk1LLz WORD 1337h

negUnit SBYTE -1

half BYTE 0.5d

Difference SWORD ?

starField BYTE 2000 DUP("*")

bigLoss SDWORD -50000

.code
main PROC

FillRegs:

    mov eax,usPop           ;store 3139000000d into eax
    sub eax,my1337Sk1LLz    ;subtracts 1337h from usPop in eax
    mov Difference, eax     ;stores eax into Difference

    mov edx,bigLoss         ;stores -50000 into edx

    mov eax,secondE         ;store 0E00 into eax
    mov ah,'A'              ;store string A into ah 
    mov al,'X'              ;store string X into al

    mov ebx,secondE         ;store 0E00 into ebx
    mov bh,'B'              ;store string B into bh
    mov bl,'X'              ;store string X into bl

    call DumpRegs           ;shows Registers

    exit                    ;exits
    main ENDP

END main

0 回复 | 直到 10 年前

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icktoofay pcp 13 年前

这两行是你的问题:

sub eax,my1337Sk1LLz    ;subtracts 1337h from usPop in eax
mov Difference, eax     ;stores eax into Difference

eax 是32位,但都是 my1337Sk1LLz 和 Difference 是16位。

有两种方法可以解决这个问题:

更改的大小 1337SK1LZ马来西亚令吉 和 差异 . 现在你的类型是 WORD 和 SWORD ,分别是。你可以把它们改成 DWORD 和 SDWORD 使它们变成32位。
零扩展和截断。 你需要另一个登记册。我会用 edx 因为你好像不在那里用。首先,你需要签延期 1337SK1LZ马来西亚令吉 :
```
movzx edx, my1337Sk1LLz  ; move, zero-extended, my1337Sk1LLz into EDX
```
然后你可以做减法运算:
```
sub eax, edx  ; they're the same size now so we can do this
```
那么你就可以把 eax公司 进入之内 差异 ,丢弃高位字:
```
mov Difference, ax
```